import sys
from PyQt5.QtWidgets import QWidget,QPushButton,QFrame,QColorDialog,QApplication
from PyQt5.QtGui import QColor

class Example(QWidget):
    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        col=QColor(0,0,0)
        self.btn=QPushButton('Dialog',self)
        self.btn.move(20,20)

        self.btn.clicked.connect(self.showDialog)

        self.frm=QFrame(self)
        self.frm.setStyleSheet("QWidget {background-color:%s}" % col.name())
        self.frm.setGeometry(130,22,100,100)

        self.setGeometry(300,300,250,180)
        self.setWindowTitle('Color dialog')
        self.show()

    def showDialog(self):
        col=QColorDialog.getColor()
        if col.isValid():
            self.frm.setStyleSheet("QWidget {background-color: %s}"% col.name())

if __name__=='__main__':
    app=QApplication(sys.argv)
    ex=Example()
    sys.exit(app.exec_())

